The Difference Between FUEL And HYDRATION In A Marathon

Performance in a marathon is about controlling the controllable. Train hard, recover well and the variables associated with fitness are minimised. Practice pace judgement and the likelihood that you reach your goal begins to increase. Fuel and hydrate properly and you maximise the chances of avoiding ‘the wall’ or the myriad of other names associated with struggling through the last 10-12km.

Fuelling is a strategy of supplementing the bodies diminishing glycogen stores throughout long distance racing. There are two sides to the coin of fuelling: hydration and carbohydrates. The key is maximising the bodies ability to utilise both, so absorption and availability is king.

The general consensus in the scientific community is that the body generally has enough glycogen ‘on board’ to get you to around 75-90 minutes of hard running. However, by implementing an effective hydration and carbohydrate protocol, gains can be anywhere from 2-15% based on where you’re racing.

When it comes to fuelling for the marathon there is plenty of conflicting information floating around, yet there are a few in the scientific community that (a) specialise in this area (b) are runners themselves and work with elites. One of the few to be (c) all of the above, is Trent Stellingwerff.

Stellingwerff provides physiology and nutrition expertise to Canada’s national rowing, track & field and triathlon teams, as well as leading their Innovation and Research division. He is currently one of the leading-brains in the field, and below we have implemented some of his recommendations into a guide for any race where you’re likely to be on your feet for longer than those 70-90 minutes.

SOS athlete Patrick Rizzo finishing the London Marathon in 12th place. April, 2013. Rizzo has found that without effective fuelling & hydration he is unable to get the most out of his fitness and regularly practices taking on fluids in training.

Where does SOS fit?

SOS is an Oral Rehydration Solution (ORS) and one of the most effective ways to absorb electrolytes outside of an IV Drip, which would be difficult to utilise while racing…

What about the Carbohydrate?

The traditional fuel of choice for many marathoners has been gels. More recently, many athletes have started to utilise carbohydrate-dense drinks such as Maurten.

Getting Started

Although there are some useful ‘general guidelines’, we all have different needs, so it’s always a good idea to complete a bit of an amateur sweat test during training. It is as simple as it sounds: track your weight pre and post run. The metric system makes this a lot easier as 1L of sweat is equal to 1 Kg of body weight. Ideally you will end up somewhere between the 2-5% range. That will give you an idea of how much fluid you will need to get down to keep the tank running. Try it across varying types of weather and distances to get a bit of an idea of how your body is working to keep itself cool.

Laura Thweatt successfully implemented her favourite Mango SOS as a key part of her fuelling for the NYC Marathon in 2015 where she was 1st American.

What type of fuel?

Not all gels and drinks are created equal, and neither are all sugars. Stellingwerff recommends a blend of glucose and fructose, with studies indicating that this allows between 20-40% greater absorption and delivery of carbohydrate over glucose alone. This is because there are separate transporters for glucose and fructose in the intestine, meaning that a glucose/fructose blend of around 2:1 results in increased uptake of carbohydrate and more delivery to the muscles.

Various brands of gels and drinks offer a wide range of consistency and viscosity that is all a matter of personal preference. What is important is the glucose/fructose ratio. Look for maltodextrin (which is glucose as well) or sucrose and fructose as the first two ingredients.

The Rule of 15

The ‘Rule of 15’ is basically consuming something close to 15 grams of carbohydrate every 15 minutes and 150 mL of fluid. Don’t overthink the exact numbers, the key is being there or there about over the course of an hour (ish), which is around 60g per hour of carb’s and 600 mL of fluids.

In order to limit GI distress and maximise absorption while also working to the guidelines above, we have found that it’s a good idea to separate your fuel and hydration. Rather using a generic sports drink that is trying to be both, alternate SOS and a gel or drink such as Maurten at each available station. This way you can let your body focus on one thing at a time while still getting your fuel requirements.

Separating hydration and fuel also allows for a greater ability to modify consumption based on weather without sacrificing glycogen intake. If it’s hot, you can drink more and vice versa. Hydration needs can vary; glycogen requirements do not.

Take your time with your fluids; you don’t need to get your whole bottle down in 30 seconds. It’s not uncommon to see those at the top end of the field sipping over the course of a kilometre. It’s easier on the GI system and settles with less distress.

Practice makes perfect

Running is fast can be hard, and drinking while running fast is even harder. With that in mind it’s important to practice your fluids in training as much as is feasibly possible. Set up a foldout table or put bottles on the hood of your car. If you’re carrying bottles, practice long runs and workouts with your fuel belt or bottle in hand. If you are leaving hydration purely up to what the race provides, try and get as efficient as you can with drinking out of paper cups.

Don’t let all the training you have done fall apart because of an inadequate fuelling strategy. You can be as fit as you have ever been, but if the pump from the engine to the tank isn’t working optimally you will almost certainly run below your ability.